Project Summary The broad objective of the research is to definitively test a primate model that already shows evidence of beta amyloid (A?) plaque accumulation to determine whether there are cognitive and behavioral deficits that correlate with plaque accumulation, and whether the deficits are specifically ones also found in Alzheimer's Disease (AD) in humans. Cognitive tasks that show a unique decline in AD patients include immediate forgetting, category set shifting failures, and visuospatial search failures. A matching-to-sample task, a traditional memory task for animals, is employed to test forgetting over short periods of time of various sets of objects. It is also used to measure accuracy and delays coincident with target objects that are not central to view or target objects that have overlapping features and are thus harder to detect in visual search. A dimensional change card sorting (DCCS) task commonly used to test toddlers who also fail to shift sets is used to measure resistance to switch in the primate model. Individual differences in cognitive tasks and in general vital behaviors (foraging, social, motor) are tracked over time and used in a multiple regression analysis to determine the best predictor of A? plaque accumulation and neural degeneration post mortem. Immunohistochemical assessment in brain tissue will verify the presence of A? plaques through the use of antibody tagging and cell death through the use of Nissl stain. If successful, the methods will elucidate proper tasks for AD-like cognitive measurement in primate models. Finding a good set of tasks to evaluate primates who naturally accumulate A? plaques should lead to new medical and training procedures for AD that can be developed in primate models.